(A) Graph showing the percentage of GFP-positive cells after DR-GFP analysis. U2OS cells were infected with I-SceI adenovirus and knocked down for BRCA1 or CHAMP1 using siRNA. N = 3 biologically independent experiments. Error bars indicate SD, and p values were calculated using two-tailed Student’s t test, ***p < 0.001.
(B) Graph showing the percentage of GFP-positive cells after EJ5-GFP analysis. U2OS cells were infected with I-SceI adenovirus and knocked down for 53BP1 or CHAMP1 using siRNA. N = 3 biologically independent experiments. Error bars indicate SD, and p values were calculated using two-tailed Student’s t test, ***p < 0.001, **p < 0.01, *p < 0.05.
(C) Quantification of resected ssDNA measured by SMART assay in U2OS cells treated by siControl or siRNAs targeting CHAMP1 for 48 h. Approximately 50 fibers were counted per experiment. Error bars indicate SD, and p values were calculated using Student’s t test, ***p < 0.001.
(D) (Left) Representative images of RAD51 foci formation in wild-type and two CHAMP1 knockout U2OS cell lines 6 h after 5Gy IR treatment. Scale bar, 5 μm. (Right) Quantification of >10 RAD51 foci. n = 3 biologically independent experiments. Error bars indicate SD, ***p < 0.001. Statistical analysis was performed using two-tailed Student’s t test.
(E) 3-day cytotoxicity analysis of wild-type and two CHAMP1 knockout RPE1(p53−/−) cell lines treated with various doses of olaparib; n = 3 independent experiments. Wild-type versus CHAMP1-KO#1, ***p < 0.001; wild-type versus CHAMP1-KO#2; error bars indicate SD, ***p < 0.001; statistical analysis was performed using two-way ANOVA.
(F) 3-day cytotoxicity analysis of wild-type and two CHAMP1 knockout U2OS cell lines treated with various doses of olaparib. Cell viability was detected by CellTiter-Glo (Promega), n = 3 independent experiments. Wild-type versus CHAMP1-KO#1, ***p < 0.001; wild-type versus CHAMP1-KO#2; error bars indicate SD, ***p < 0.001; statistical analysis was performed using two-way ANOVA.